Week 2- 2R Robotic Arm Challenge

Aim: To simulate the forward kinematics of a 2R robotic arm

Principle :

A 2R robotic arm has 2 links and 2 rotational axis

one link is connected to the base while other link is connected to the first link.

link1 moves at angle thetha1 and link2 moves at an angle thetha 2.

The position of the link 1 and link2 is x0,y0,x1,x2,y1,y2.

since the starting point of the link1 is connected to the base its position will be zero. Hence

x=0,y=0.

The position of the ending point of the link1 will be

x1 = l1cosd(thetha1)

y1 = l1sind(thetha1)

where l1 and l2 are length of the link1 and link2 respectively.

The ending point of the link1 and starting point of the link2 is same

The position of the ending point of the link2 is

X2 = x1+l2cosd(thetha2)

y2 = y1+l2sind(thetha2)

Program

clear all
close all
clc

%inputs
l1 =1;
l2= 0.5;

% angles for link1 and link2
theta1 = linspace(0,90,40);
theta2 = linspace(0,90,40);

ct = 1;
for i = 1:length(theta1)
    Thetha1= theta1(i);
    for j=1:length(theta2)
        Thetha2 = theta2(j);

        x0=0;
        y0=0;

        x1=l1*cosd(Thetha1);
        y1=l1*sind(Thetha1);

        x2=x1+l2*cosd(Thetha2);
        y2=y1+l2*sind(Thetha2);

        plot([x0,x1],[y0,y1],[x1,x2],[y1,y2],'linewidth',3);
        axis([-0.1 1.5 0 1.5]);
        pause(0.1);
        M(ct) = getframe(gcf);
        ct = ct +1;
    end 
end
movie(M)
videofile = VideoWriter('animation.avi','Uncompressed AVI');
open(videofile)
writeVideo(videofile,M)
close(videofile)

Explanantion of the code

clear all function is used to clear all the variables and memory cache

close all function is used to clear the plots and graphs

clc is used to clear the command window

l1 and l2 are the inputs of the length of the robotic arm

Since both link1 and link2 moves at the various angle of theta linspace command is used

The linspace function in MATLAB provides us with an array/matrix comprising the desired number of values starting from and ending at a declared value.

Since each value of thetha 1 and thetha 2 is to be executed For loop is used

where i and j are the variables

to exit the for loop end command is used

After the values are generated we need to plot a graph hence Plot command is used

Pause command is used to determine the speed of the animation

once the animation is done we need to caputure the frames.for that we use

M(ct)=getframe(gcf)

The frames are stored in a array called M

Onced the frame are stored we need to create a movie hence function M is used

once the movie is created we need to save a video file with a name hence videowriter command is used where is the name of the video and format is entered

Open(videofile) open video file saved

close(videofile) closes the video

Problems faced:

once the Plot is created .The movement of link2 was not showing properly

To rectify Axis command is used to fix the axis in detremined value

Output

The animation for the above program is shared in the link below

https://drive.google.com/file/d/1kqu3boNy1qi3mxCkDaNWM3ozBAGAYp8F/view?usp=sharing

The display of output screen